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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    
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<script>
    let arr = [12,56,96,25];
    console.log(arr[2]);//96
    let arr2 = ['tom',30.1,true,,,,];
    console.log(arr2[4]);
    arr2[4] = null;
    console.log(arr2[4]);
    //遍历数组
    console.log(arr.length);//获取数组长度
    for(let i = 0;i<arr.length;i++){
        console.log(arr[i]);
    }
    //找出数组score中的最大值，算出数组平均数
    let score = [89,67,59,90,54,77,83,88.5,43,10,68];
    let max = score[0];
    let sum = 0;
    for(let i = 0;i<score.length;i++){
            if(score[i]>max){
                    max = score[i];
            }
            sum = sum+score[i];//sum+=score[i];
    }
        let avg = sum / score.length;
        console.log('最大值是:'+max);
        console.log('平均分数为：'+avg);
        score[1000] = 88;
        console.log(score[1000]);
        console.log(score.length);
        for(let i = 0;i<score.length;i++){
            console.log(score[i]);
        }
        delete score[1000];
        console.log(score[1000]);
</script>
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